JP2010025412A - Refrigerating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve durability of an evaporator by making the evaporator hardly damaged by thermal stress by minimizing temperature difference between a refrigerant and a heat medium in the evaporator, in a refrigerating device comprising a refrigerant circuit. <P>SOLUTION: In the refrigerant circuit 10, an evaporating pressure adjustment valve 17 is disposed between the evaporator 14 and a suction side of a compressor 11, to adjust the evaporating pressure of the refrigerant in the evaporator 14 so that the temperature difference between the refrigerant flowing in the evaporator 14 and the heat medium exchanging heat in the evaporator 14 becomes less than a prescribed value. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a refrigeration apparatus including a refrigerant circuit in which a compressor, a condenser, an expansion mechanism, and an evaporator are sequentially connected, and particularly relates to measures for improving the durability of the evaporator.

  Conventionally, a refrigeration apparatus having a refrigerant circuit in which a compressor, a condenser, an expansion mechanism, and an evaporator are connected in order is known. In such a refrigeration apparatus, in the condenser, the refrigerant flowing in the condenser dissipates heat to the outside (other heat medium) and condenses, and in the evaporator, the refrigerant flowing in the evaporator passes outside ( By absorbing heat from another heat medium) and evaporating, the air is radiated or absorbed into the air in the room or in the room, and air conditioning in the room or cooling in the room is performed.

  Further, as disclosed in, for example, Patent Document 1, a primary side circuit and a secondary side circuit that respectively form a refrigerant circuit are connected by an evaporator of the primary side circuit, and the primary side is connected by the evaporator. There is also known one configured to perform heat exchange between the refrigerant in the circuit and the refrigerant in the secondary side circuit. Here, as the evaporator, a plate-type heat exchanger in which two flow paths capable of heat exchange are formed is generally used.

Further, recently, a secondary circuit in which a heat medium such as water or brine circulates is provided for the primary circuit composed of the refrigerant circuit, and the refrigerant of the primary circuit is provided in the evaporator of the primary circuit. A chilling unit configured to radiate heat to a heat medium circulating in the secondary circuit is known. Such a chilling unit is used, for example, for cooling a silicon wafer or the like in a semiconductor manufacturing process.
JP 2006-57869 A

  However, when heat exchange is performed between the refrigerant flowing in the evaporator and the other heat medium as described above, a thermal stress is generated in the evaporator due to a temperature difference between the refrigerant and the heat medium. If the temperature difference is large, a large thermal stress is generated in the evaporator. When the temperature of the heat medium in the secondary circuit greatly fluctuates due to the load on the use side, thermal stress is repeatedly generated in the evaporator, and the evaporator may be damaged by the thermal stress.

  In particular, in the case of the above-described chilling unit for cooling a semiconductor, the heat load on the use side fluctuates greatly, and the temperature of the heat medium in the secondary circuit also changes greatly. Therefore, the refrigerant and heat medium in the evaporator The temperature difference is easily changed, and the evaporator is easily damaged by thermal stress.

  The present invention has been made in view of such a point, and an object of the present invention is to minimize a change in the temperature difference between the refrigerant and the heat medium in the evaporator in the refrigeration apparatus including the refrigerant circuit. Thus, the durability of the evaporator is improved by making the evaporator less susceptible to damage by thermal stress.

  In order to achieve the above object, in the refrigeration apparatus (1) according to the present invention, the evaporation pressure in the evaporator (14) is adjusted between the evaporator (14) and the suction side of the compressor (11). An evaporation pressure adjusting means (17) is provided to prevent the temperature difference between the refrigerant flowing through the evaporator (14) and the heat medium that exchanges heat with the refrigerant in the evaporator (14) as much as possible.

  Specifically, in the first invention, a compressor (11), a condenser (12), an expansion mechanism (13), and an evaporator (14) are sequentially connected to perform a vapor compression refrigeration cycle. A refrigeration apparatus including a refrigerant circuit (10) is an object.

  Between the evaporator (14) of the refrigerant circuit (10) and the suction side of the compressor (11), the refrigerant flowing in the evaporator (14) and the refrigerant (heat) are heated by the evaporator (14). It is assumed that an evaporating pressure adjusting means (17) for adjusting the evaporating pressure of the refrigerant in the evaporator (14) is provided so that the temperature difference with the heat medium to be exchanged is a predetermined value or less.

  With the above configuration, the evaporation pressure of the refrigerant flowing through the evaporator (14) is adjusted by the evaporation pressure adjusting means (17) provided between the evaporator (14) and the suction side of the compressor (11). Thus, the evaporation temperature of the refrigerant can be changed according to the heat medium to be heat-exchanged by the evaporator (14). That is, with the above-described configuration, the evaporator (14) is damaged by thermal stress due to the temperature difference between the temperature of the refrigerant flowing through the evaporator (14) and the heat medium exchanging heat in the evaporator (14). Therefore, the durability of the evaporator (14) can be improved.

  In the above-mentioned configuration, it is assumed that a use side circuit (40) connected to the evaporator (14) and in which the heat medium that exchanges heat with the refrigerant in the evaporator (14) circulates is provided (second circuit). invention). As described above, when the use side circuit (40) is provided for the refrigerant circuit (10) as the primary side circuit so as to exchange heat with the refrigerant in the evaporator (14) of the refrigerant circuit (10), When the temperature change of the heat medium circulating in the use side circuit (40) is large, the temperature change of the evaporator (17) is also increased correspondingly, and the fluctuation of the thermal stress generated in the evaporator (14) is increased. growing. Therefore, in such a configuration, the durability of the evaporator (14) can be effectively improved by applying the configuration of the first invention.

  Further, a heat medium temperature detecting means (PT) for detecting an evaporator outlet temperature of the heat medium in the use side circuit (40), and an evaporator outlet of the heat medium detected by the heat medium temperature detecting means (PT) Control means (50) for controlling the evaporation pressure adjusting means (17) is preferably provided so as to adjust the evaporation pressure of the refrigerant in the evaporator (14) based on the temperature (third) invention).

  As a result, the temperature of the heat medium in the evaporator (14) can be accurately detected, and the temperature difference between the heat medium and the refrigerant flowing in the evaporator (14) is as much as possible according to the temperature of the heat medium. It becomes possible to adjust the evaporation pressure of the refrigerant in the evaporator (14) so as to be small. Therefore, the fluctuation of the thermal stress in the evaporator (14) can be minimized.

  In particular, the control means (50) is arranged so that the temperature difference between the refrigerant and the heat medium in the evaporator (14) increases as the temperature of the heat medium at the evaporator outlet increases. It is preferable to control (17) (fourth invention).

  When the temperature of the heat medium flowing through the use side circuit (40) is high, it is difficult to raise the temperature of the refrigerant in the primary side circuit (10) to that temperature, so the refrigerant and heat medium in the evaporator (14) It is difficult to keep the temperature difference between and constant. Therefore, as described above, the higher the temperature of the heat medium at the outlet of the evaporator (14), the larger the temperature difference between the refrigerant and the heat medium in the evaporator (14). By adjusting the evaporating pressure of the refrigerant in the evaporator (14), the temperature difference with the refrigerant is made as small as possible when the temperature of the heat medium is low, while the refrigerant that can be realized when the temperature of the heat medium is high In this temperature range, the temperature difference between the refrigerant and the heat medium can be made as small as possible. Therefore, even when the heat medium causes a temperature change in a relatively wide range, the thermal stress generated in the evaporator (14) can be reduced as much as possible.

  Moreover, it is preferable that the said evaporation pressure adjustment means is equipped with the motor operated valve (17) (5th invention). In this way, the evaporation pressure of the evaporator (14) can be reliably adjusted by the evaporation pressure adjusting means (17) provided between the evaporator (14) and the suction side of the compressor (11). The configurations of the first to fourth inventions can be realized.

  As described above, according to the present invention, the temperature difference between the refrigerant and the heat medium in the evaporator (14) is not more than a predetermined value between the evaporator (14) and the suction side of the compressor (11). Since the evaporation pressure adjusting means (17) for adjusting the evaporation pressure of the refrigerant in the evaporator (14) is provided so as to become, the thermal stress caused by the temperature difference between the refrigerant and the heat medium in the evaporator (14) Therefore, it is possible to prevent the evaporator (14) from being damaged as much as possible. Therefore, the durability of the evaporator (14) can be improved.

  According to the second invention, in the configuration in which the utilization side circuit (40) in which the heat medium circulates is connected to the evaporator (14), the configuration of the first invention is applied, so that the evaporation The durability of the vessel (14) can be effectively improved.

  According to the third invention, the evaporation pressure adjusting means (17) adjusts the evaporation pressure of the evaporator (14) based on the evaporator outlet temperature of the heat medium. It is possible to set the evaporation temperature of the refrigerant at an appropriate temperature according to the temperature of the heat medium, and the durability of the evaporator (14) can be improved more reliably. In particular, according to the fourth invention, the evaporating pressure adjusting means (17) is configured such that the temperature of the refrigerant and the heat medium in the evaporator (14) increases as the outlet temperature of the evaporator (14) of the heat medium increases. In order to adjust the evaporation pressure of the refrigerant in the evaporator (14) so as to increase the difference, the temperature difference between the heat medium and the refrigerant is reduced as much as possible, and the evaporator (14) is subjected to thermal stress. Damage can be reduced.

  Furthermore, according to the fifth invention, the evaporating pressure adjusting means includes the motor-operated valve (17), so that the configurations of the first to fourth inventions can be reliably realized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the following description of the preferred embodiment is merely illustrative in nature and is not intended to limit the present invention, its application, or its use.

−Configuration−
In FIG. 1, the outline of the piping system diagram of the freezing apparatus which concerns on embodiment of this invention is shown. The refrigeration apparatus shown in FIG. 1 is configured, for example, as a brine chilling unit (1) for cooling a silicon wafer in a semiconductor manufacturing process. The chilling unit (1) includes a refrigerant circuit (10) in which refrigerant circulates, a cooling water circuit (30) in which cooling water circulates, and a brine (heat medium) cooled by the refrigerant in the refrigerant circuit (10). Is provided with a utilization side circuit (40) in which the controller circulates and a controller (50) as control means. That is, the chilling unit (1) is configured to supply the brine cooled by the refrigerant in the refrigerant circuit (10) to the semiconductor production equipment on the usage side via the usage side circuit (40). Has been.

(Refrigerant circuit)
The refrigerant circuit (10) includes a supercooling heat exchanger (15) and a supercooling expansion valve (16) in addition to the compressor (11), the condenser (12), the expansion valve (13), and the evaporator (14). ), An evaporation pressure adjusting valve (17) (evaporating pressure adjusting means) is connected by piping. Thereby, in the refrigerant circuit (10), the refrigerant circulates in the circuit (10), and a vapor compression refrigeration cycle is performed.

  The compressor (11) is a high-pressure dome type scroll compressor. The compressor (11) is configured as a variable capacity compressor whose rotation speed is variable by inverter control. The discharge side of the compressor (11) is connected to the condenser (12) via a discharge gas pipe (21). On the other hand, the suction side of the compressor (11) is connected to the evaporator (14) via a suction gas pipe (22). An injection pipe (27), which will be described later, is connected to an intermediate pressure compression chamber (hereinafter also referred to as an intermediate pressure chamber) of the compressor (11). That is, the compressor (11) is configured to be capable of injecting an intermediate pressure refrigerant into the intermediate pressure chamber. In this way, by adopting a configuration in which the refrigerant can be injected into the intermediate pressure chamber, the discharge temperature of the compressor (11) can be adjusted, and the compressor (11) can be protected.

  The condenser (12) is a so-called plate heat exchanger in which a plurality of plates are stacked so as to form a flow path between the plates. The condenser (12) is formed with a refrigerant flow path (12a) and a cooling water flow path (12b), and the refrigerant flow path (12a) is disposed on the refrigerant circuit (10) side with the cooling water flow path ( 12b) is connected to the coolant circuit (30) side. Specifically, the condenser (12) has one end side of the refrigerant flow path (12a) connected to the discharge side of the compressor via the discharge pipe (21) of the refrigerant circuit (10), The other end side of the refrigerant channel (12a) is connected to the supercooling heat exchanger (15) via the first liquid pipe (23). The cooling water flow path (12b) of the condenser (12) is connected to the cooling water pipe (31) of the cooling water circuit (30) at both ends. That is, the condenser (12) is configured to exchange heat between the refrigerant flowing in the flow paths (12a, 12b) and the cooling water. By this heat exchange, the condenser (12) can condense the refrigerant flowing in the refrigerant circuit (10). The cooling water pipe (31) of the cooling water circuit (30) is connected to a cooling tower or a pump (not shown) so that cooling water cooled by the cooling tower flows.

  The expansion valve (13) is an electronic expansion valve whose opening degree can be adjusted. The expansion valve (13) is provided on the second liquid pipe (24) connecting the supercooling heat exchanger (15) and the evaporator (14).

  Similarly to the condenser (12), the evaporator (14) is also constituted by a so-called plate heat exchanger. The evaporator (14) is formed with a primary channel (14a) and a secondary channel (14b), and the primary channel (14a) is connected to the refrigerant circuit (10) side. The secondary side flow path (14b) is connected to the use side circuit (40). Specifically, in the evaporator (14), one end side of the primary channel (14a) is connected to the expansion valve (13) via the second liquid pipe (24), while the primary side channel (14a) The other end side of the flow path (14a) is connected to the suction side of the compressor (11) via the suction gas pipe (22). Further, one end side of the secondary side flow path (14b) of the evaporator (14) is connected to the delivery pipe (46) of the use side circuit (40), while the secondary side flow path (14b) The other end side is connected to the tank (41) through the second return pipe (43) of the use side circuit (40). The evaporator (14) is configured to exchange heat between the refrigerant flowing through these flow paths (14a, 14b) and the brine. By this heat exchange, in the evaporator (14), the brine in the use side circuit (40) can be cooled by the refrigerant.

  Like the condenser (12) and the evaporator (14), the supercooling heat exchanger (15) is a so-called plate heat exchanger, and is configured to exchange heat between the refrigerant and the refrigerant. Has been. Specifically, a first flow path (15a) and a second flow path (15b) are formed in the supercooling heat exchanger (15), and one end side of the first flow path (15a) The first liquid pipe (23) is connected, and the other end is connected to the second liquid pipe (24). One end side of the second flow path (15b) is connected to a branch pipe (26) branched from the second liquid pipe (24), and the other end side is connected to an intermediate pressure chamber of the compressor (11). Connected to the injection tube (27). Thus, the supercooling heat exchanger (15) exchanges heat between the refrigerant flowing in the first flow path (15a) and the refrigerant flowing in the second flow path (15b). The refrigerant flowing through the first flow path (15a) is configured to be cooled.

  The supercooling expansion valve (16) is an electronic expansion valve whose opening degree is adjustable. The supercooling expansion valve (16) is provided on the branch pipe (26). When the refrigerant decompressed by the supercooling expansion valve (16) flows in the second flow path (15b) of the supercooling heat exchanger (15), the refrigerant of the supercooling heat exchanger (15) It absorbs heat from the refrigerant in one flow path (15a) and evaporates.

  As a feature of the present invention, an evaporation pressure adjusting valve (17) as an evaporation pressure adjusting means is provided on the suction gas pipe (22) between the evaporator (14) and the compressor (11). It has been. The evaporating pressure adjusting valve (17) is an electronic expansion valve (motorized valve) whose opening degree can be adjusted. By providing such an evaporation pressure adjusting valve (17) on the suction side of the compressor (11) (between the evaporator (14) and the compressor (11)), the evaporation pressure adjusting valve (17) In addition, the evaporation pressure of the refrigerant in the evaporator (14) located on the upstream side of the refrigerant flow path can be adjusted, and the evaporation temperature of the refrigerant in the evaporator (14) can be adjusted.

  The refrigerant circuit (10) is provided with various sensors and pressure switches. Specifically, the discharge gas pipe (21) is provided with a discharge temperature sensor (61), a discharge pressure sensor (62), and a high pressure switch (63). An outlet refrigerant temperature sensor (64) is provided at the outlet side of the supercooling heat exchanger (15) of the second liquid pipe (24), and an outlet is provided at the outlet side of the evaporator (14) of the intake gas pipe (22). A refrigerant temperature sensor (65) and a low pressure side pressure sensor (66) are respectively provided. Here, the discharge temperature sensor (61) and the outlet refrigerant temperature sensor (64, 65) detect the temperature of each pipe such as the discharge gas pipe (21), and the high pressure switch (63) is the discharge pressure. Is detected, and the chilling unit (1) is urgently stopped at abnormally high pressure. The discharge pressure sensor (62) detects the discharge pressure of the compressor (11), and the low pressure side pressure sensor (66) detects the pressure on the low pressure side in the refrigerant circuit (10).

(User side circuit)
The use side circuit (40) is configured by connecting a tank (41), an evaporator (14), and a use side (not shown) in order by piping. The use side circuit (40) is filled with brine as a heat medium, and the brine circulates between the evaporator (14) and the use side so as to reach a predetermined set temperature. Temperature-controlled brine is supplied to the user side.

  In the use side circuit (40), the first return pipe (42) of the brine extending from the use side is connected to the tank (41). A second return pipe (43) extending to the evaporator (14) is also connected to the tank (41).

  The tank (41) is divided into two spaces (41a, 41b) while the spaces (41a, 41b) are communicated with each other at the lower part of the tank (41). A partition plate (41c) extending from the upper part to a predetermined depth is provided. A heater (44) is disposed in one space (41a) of the spaces (41a, 41b) partitioned by the partition plate (41c), and a pump is disposed in the other space (41b). (45) is arranged. The pump (45) is configured to send the brine in the space (41b) of the tank (41) to the evaporator (14) through the second return pipe (43).

  The delivery pipe (46) is connected to one end side of the secondary flow path (14b) of the evaporator (14), while the second return pipe (43) is connected to the other end side. Yes. As a result, the brine sent out by the pump (45) in the tank (41) flows through the secondary flow path (14b) of the evaporator (14), and the primary of the evaporator (14). After being cooled by the refrigerant flowing in the side flow path (14a), it is sent to the use side by the delivery pipe (46). The delivery pipe (46) is provided with a check valve (CV). This check valve (CV) allows only the refrigerant flow in the direction of the arrow shown in FIG.

  Various sensors are provided in the use side circuit (40). Specifically, the first return pipe (42) is provided with a brine temperature sensor (71) for detecting the temperature of the brine, and the temperature of the heater (44) is set in the tank (41). A heater temperature sensor (72) is provided for detection. The second return pipe (43) has a brine pressure sensor (73) and an evaporator inlet temperature sensor (74), and the delivery pipe (46) has a platinum thermometer (PT) on the outlet side of the evaporator (14). (Heat medium temperature detection means) is provided. Further, the tank (41) is provided with liquid level detection sensors (75, 76) for detecting the liquid level in the tank (41). Here, the brine pressure sensor (73) is for detecting the pressure of the brine in the use side circuit (40), and the evaporator inlet temperature sensor (74) is provided in the second return pipe (43). This is for detecting the temperature on the inlet side of the evaporator (14). The platinum thermometer (PT) is for detecting the temperature of the brine at the outlet of the evaporator (14), and is a temperature sensor using a platinum temperature resistor.

(controller)
The controller (50) is a compressor (11) based on signals output from various sensors (61, 62,...) And switches (63) in the refrigerant circuit (20) and the use side circuit (40). And an expansion valve (13, 16), an evaporation pressure adjusting valve (17), and a pump (45). Except for the control of the evaporating pressure adjusting valve (17), it is the same as the controller (50) of the conventional chilling unit, so only the part relating to the control of the evaporating pressure adjusting valve (17) will be described below.

  The controller (50) determines the temperature of the brine and refrigerant in the evaporator (14) based on the temperature of the evaporator outlet of the brine in the user side circuit (40) (detection result in the platinum thermometer (PT)). The opening degree of the evaporating pressure adjusting valve (17) is controlled so that the difference is not more than a predetermined temperature difference that is not easily damaged by thermal stress in the evaporator. Specifically, the controller (50) is based on a timer unit (51) for determining the timing for adjusting the opening of the evaporation pressure adjusting valve (17) and the temperature of the outlet of the evaporator of the brine. A valve control amount calculation unit (52) for calculating a control amount of the evaporation pressure adjusting valve (17). That is, when the controller (50) detects that the timer unit (51) calculates the control amount of the evaporation pressure adjustment valve (17) and performs drive control, the controller (50) detects the valve control amount calculation unit (52 ), The control amount of the evaporation pressure adjusting valve (17) is obtained by the method described later, and the evaporation pressure adjusting valve (17) is controlled.

-Driving action-
Next, the operation of the chilling unit (1) having the above configuration will be described.

(Refrigerant circuit)
When the compressor (11) is operated in the refrigerant circuit (10), the compressed gas refrigerant is discharged from the compressor (11). The gas refrigerant flows through the discharge gas pipe (21) and is introduced into the refrigerant flow path (12a) of the condenser (12). In the refrigerant flow path (12a) of the condenser (12), the introduced refrigerant dissipates heat into the cooling water flowing in the cooling water flow path (12b) of the condenser (12) and condenses. The refrigerant condensed in the condenser (12) flows out of the condenser (12) and flows into the first flow path (15a) of the supercooling heat exchanger (15) through the first liquid pipe (23). .

  The refrigerant flowing through the first flow path (15a) of the supercooling heat exchanger (15) is reduced in pressure when flowing through the second liquid pipe (24) and passing through the expansion valve (13). The refrigerant flows into the branch pipe (26) on the upstream side of the expansion valve (13). A part of the refrigerant flowing into the branch pipe (26) is depressurized through the supercooling expansion valve (16) and flows into the second flow path (15b) of the supercooling heat exchanger (15). The liquid refrigerant flowing through the first flow path (15a) exchanges heat and evaporates, and the liquid refrigerant flowing through the first flow path (15a) is cooled to a predetermined low temperature. The refrigerant evaporated in the supercooling heat exchanger (15) flows through the injection pipe (27) and is injected into the intermediate pressure chamber of the compressor (11).

  On the other hand, the refrigerant decompressed by the expansion valve (13) flows into the primary channel (14a) of the evaporator (14). In the primary side flow path (14a), the refrigerant flowing in absorbs heat from the brine flowing in the secondary side flow path (14b) and evaporates. The refrigerant evaporated in the evaporator (14) flows out of the evaporator (14), passes through the evaporation pressure regulating valve (17), and is then sucked into the compressor (11) through the suction gas pipe (22). Is done. In the compressor (11), the sucked refrigerant is compressed and discharged again. Thereby, in the refrigerant circuit (10), the refrigerant circulates in the circuit (10) to perform a refrigeration cycle.

(User side circuit)
When the pump (45) is operated in the use side circuit (40), the brine circulates in the use side circuit (40). Specifically, the brine that has absorbed heat from the object on the use side flows through the first return pipe (42) and is introduced into the tank (41). The brine introduced into the tank (41) is heated by the heater (44) in the tank (41), and then the pump (45) passes through the second return pipe (43) to the evaporator (14). It is sent out to the secondary channel (14b). When heating by the heater (44) is unnecessary, the heater (44) does not operate.

  The brine that has flowed into the secondary channel (14b) of the evaporator (14) exchanges heat with the refrigerant flowing in the primary channel (14a) of the evaporator (14). As a result, the brine is cooled by releasing heat to the refrigerant. The brine cooled by the evaporator (14) flows to the delivery pipe (46) and is supplied to the use side. The brine that has absorbed heat from the object on the use side returns to the tank (41) again through the first return pipe (42).

(Evaporation pressure control)
In the operation as described above, in the evaporator (14) of the refrigerant circuit (10), the temperature of the refrigerant flowing in the primary channel (14a) and the brine flowing in the secondary channel (14b) Due to the difference, thermal stress is generated. And as shown in FIG. 2, while the evaporation temperature of the refrigerant in the evaporator (14) is substantially constant (broken line in the figure), for example, like a chilling unit used in a semiconductor manufacturing process, Depending on the operation state, the temperature of the brine flowing in the use side circuit (40) may fluctuate greatly (see solid line in the figure). If it does so, the fluctuation | variation of a big thermal stress will arise in the said evaporator (14) which consists of a plate heat exchanger, and this evaporator (14) may be damaged by the fluctuation | variation of this thermal stress.

  Therefore, in the present invention, the temperature difference between the brine and the refrigerant in the evaporator (14) is made as small as possible by changing the evaporation temperature of the refrigerant in accordance with the temperature change of the brine in the evaporator (14). Thus, large fluctuations in thermal stress were prevented from occurring in the evaporator (14).

  Specifically, the opening degree of the evaporation pressure adjusting valve (17) provided between the evaporator (14) and the compressor (11) is set to the temperature at the outlet side of the brine (platinum thermometer (PT ) To adjust the evaporation pressure of the refrigerant in the evaporator (14). That is, as shown in FIG. 2, the opening degree of the evaporation pressure adjusting valve (17) is reduced according to the temperature of the brine outlet side of the brine (thin solid line in the figure). ) To increase the evaporation pressure of the refrigerant in the evaporator (14), thereby increasing the evaporation temperature of the refrigerant (thick solid line in the figure) and bringing it as close as possible to the temperature of the brine.

  Specifically, the controller (50) obtains the control amount pls of the evaporation pressure adjusting valve (17) as follows.

  When the control amount calculation flow of the evaporation pressure adjusting valve (17) shown in FIG. 3 starts, first, in step S1, the timer unit (51) starts a timer and counts the time. In step S2, it is determined whether or not the time counted by the timer unit (51) has elapsed for 5 seconds. If it is determined in step S2 that 5 seconds have elapsed (in the case of YES), the process proceeds to step S3. Based on the temperature difference (ΔT2) between the refrigerant and brine in the evaporator (14), the opening adjustment amount dpls of the evaporation pressure adjusting valve (17) is calculated.

  Specifically, in step S3, ΔT2 and dpls are obtained by the following equations.

ΔT2 = PT1-f (LP1) (1)
dpls = a × P + b × I + c × D (2)
Here, in the above formula (1), PT1 is the brine temperature in the evaporator (14) (detected temperature in the platinum thermometer (PT)), and f (LP1) is the refrigerant pressure equivalent saturation temperature, In the above formula (2), for example, a = 1.0, b = 0.2, and c = 0.15, and each value of P, I, and D is given by the following formula. In the following equation, ΔT2_5 means ΔT2 5 seconds before the present, ΔT2_10 means ΔT2 10 seconds before the present, and ΔT2_20 means ΔT2 20 seconds before the present.

P = 1 × {(ΔT2−target ΔT2) − (ΔT2 — 20−target ΔT2)}
I = 1 × {(ΔT2−target ΔT2) + 2 × (ΔT2 — 5−target ΔT2)
+ (ΔT2_10−target ΔT2)}
D = 1 × {(ΔT2−target ΔT2) −2 × (ΔT2_10−target ΔT2)
+ (ΔT2_20−target ΔT2)}
In the present embodiment, the valve opening degree of the evaporating pressure regulating valve (17) is PID controlled using the above equations. However, the present invention is not limited to this, and the control is performed using a relational expression different from the above equations. You may do it.

  As shown in FIG. 4, the target ΔT2 is calculated according to the brine temperature in the evaporator (14). When the brine temperature is low, the target ΔT2 is small, that is, the evaporation is performed. While the temperature difference between the refrigerant and the brine in the vessel (14) is made as small as possible, if the temperature of the brine is high, it is impossible to raise the temperature of the refrigerant to near that temperature. ΔT2 is increased, that is, the temperature difference between the refrigerant and the brine in the evaporator (14) is increased.

  When the relationship shown in FIG. 4 is expressed by an equation, the following relationship is obtained.

<When the brine temperature is PT1 ≧ 100 ° C.>
Target ΔT2 = 50
<When the brine temperature is −30 ≦ PT1 <100 ° C.>
Target ΔT2 = 45 × (PT1-100) / 130 + 50
<When the brine temperature is PT1 <−30 ° C.>
Target ΔT2 = 5
After calculating dpls in step S3, in step S4, the opening of the evaporation pressure adjusting valve (17) is controlled using the calculated dpls. Specifically, the dpls is added to the current pls to obtain pls as a control amount, and the evaporation pressure adjusting valve (17) is controlled by the pls. Thereafter, this flow is ended, the process returns to the start (return), and the above flow is started again.

-Effect of the embodiment-
As described above, according to this embodiment, in the chilling unit (1) used in the semiconductor manufacturing process or the like, the evaporator (14) of the refrigerant circuit (10) on the primary circuit side and the suction side of the compressor (11) are connected. An evaporation pressure adjusting valve (17) is provided in between, so that the temperature difference between the temperature of the refrigerant on the primary circuit side and the temperature of the brine on the secondary circuit side in the evaporator (14) is as small as possible. Since the regulating valve (17) is controlled, it is possible to prevent the thermal stress generated by the temperature difference between the refrigerant and the brine in the evaporator (14) from fluctuating as much as possible. It is possible to prevent the evaporator (14) from being damaged by thermal stress as much as possible.

  Specifically, since the opening of the pressure regulating valve (17) is controlled based on the brine temperature at the outlet of the evaporator in the use side circuit (40) on the secondary circuit side, The evaporation pressure can be adjusted, whereby the evaporation temperature of the refrigerant in the evaporator (17) can be adjusted.

  In addition, by changing the target temperature difference ΔT2 between the brine and the refrigerant in accordance with the brine temperature at the evaporator outlet of the use side circuit (40), the brine and the refrigerant It is possible to reduce the temperature difference of the above as much as possible, and to reduce the variation of the thermal stress generated in the evaporator (14) as much as possible.

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About the said embodiment, it is good also as the following structures.

  In the above embodiment, an electronic expansion valve is used as the evaporation pressure adjusting valve. However, the present invention is not limited to this, and any means may be used as long as the evaporation pressure can be adjusted.

  Moreover, in the said embodiment, in the utilization side circuit (40) as a secondary side circuit, after a brine passes a heater (44), it flows into the secondary side flow path (14b) of an evaporator (14). However, the present invention is not limited to this, and the brine may flow into the heater (44) after passing through the secondary channel (14b) of the evaporator (14).

  Moreover, in the said embodiment, the chilling unit (1) is comprised as a freezing apparatus by providing the utilization side circuit (40) as a secondary side circuit in the refrigerant circuit (10) as a primary side circuit. However, the present invention is not limited to this, and a general air-conditioning apparatus or refrigeration apparatus configured only by the refrigerant circuit (10) may be used.

  In the above embodiment, the refrigerant circuit (10) as the primary side circuit is configured to inject the refrigerant into the intermediate pressure of the compressor (11). The refrigerant may not be injected. In this case, the supercooling heat exchanger (15) and the supercooling expansion valve (16) become unnecessary.

  As described above, the present invention provides, for example, a brine chilling unit in which heat exchange between the refrigerant circulating in the refrigerant circuit and the brine circulating in the use-side circuit is performed by the evaporator of the refrigerant circuit. It is particularly useful.

FIG. 1 is a piping system diagram illustrating a schematic configuration of a chilling unit according to the embodiment. FIG. 2 is a graph schematically showing the brine temperature in the evaporator, the refrigerant evaporation temperature in the case of the conventional configuration, and the refrigerant evaporation temperature when the present invention is applied. FIG. 3 is a diagram illustrating a flow of opening degree control of the evaporation pressure adjusting valve. FIG. 4 is a diagram illustrating the relationship between the brine temperature and the target ΔT2.

Explanation of symbols

1 Chilling unit (refrigeration equipment)
10 Refrigerant circuit
11 Compressor
12 Condenser
13 Expansion valve
14 Evaporator
17 Evaporation pressure adjustment valve (evaporation pressure adjustment means)
40 User circuit
50 controller (control means)
PT platinum thermometer (heat medium temperature detection means)

Claims (5)

A refrigeration system comprising a refrigerant circuit (10) in which a compressor (11), a condenser (12), an expansion mechanism (13), and an evaporator (14) are sequentially connected to perform a vapor compression refrigeration cycle. There,
Between the evaporator (14) of the refrigerant circuit (10) and the suction side of the compressor (11), heat is exchanged between the refrigerant flowing in the evaporator (14) and the refrigerant by the evaporator (14). A refrigeration apparatus comprising an evaporation pressure adjusting means (17) for adjusting an evaporation pressure of the refrigerant in the evaporator (14) so that a temperature difference with the heat medium becomes a predetermined value or less. In claim 1,
A refrigeration apparatus comprising a utilization side circuit (40) connected to the evaporator (14) and circulating the heat medium that exchanges heat with the refrigerant in the evaporator (14). In claim 2,
A heat medium temperature detecting means (PT) for detecting an evaporator outlet temperature of the heat medium in the use side circuit (40);
The evaporating pressure adjusting means (17) so as to adjust the evaporating pressure of the refrigerant in the evaporator (14) based on the evaporator outlet temperature of the heat medium detected by the heat medium temperature detecting means (PT). And a control means (50) for controlling the refrigeration apparatus. In claim 3,
The control means (50) is configured so that the temperature difference between the refrigerant and the heat medium in the evaporator (14) increases as the temperature of the heat medium at the evaporator outlet increases. ) Is controlled. In any one of Claims 1-4,
The evaporating pressure adjusting means includes a motor-operated valve (17).

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